Should Locking Knives be Trusted?

[Confederate]

On another forum we were discussing whether locking knives should be trusted or if, in fact, they were designed to do things non-locking knives did. I was using a little Smith & Wesson scrimshaw recently when the lock failed as I was trying to extract the blade from a UPS package I'd received. I didn't get cut, but that blade flipping back on me gave me a jolt!

Since most of us have been cut at some point in our lives, how much should we trust locking knives? If I'd been cut, would it have been my fault or the fault of the knife? Are liner locks inherently unsafe and do they become more unsafe with use? And finally, are some locking knives considered more trustworthy than others?

If any of you would care to share any horror stories about locking knives that didn't, I'd like to hear them. Thanks!

 

[Doug C]

Locks fail,shtuff happens.Some work better than others.

 

[T.K.C.]

Well, S&W's are not the most well made/ quality knife to begin with..... Yes, locks fail, but I think some are more prone than others.

 

[F3Beam]

While most are critical of liner locks, lockbacks are the ones that fold most often with me. If I get busy with one and get a tight grip, I always manage squeeze the lockback in the process and accidentally release it. Big hands maybe. I feel better with a bolt lock.

 

[Cliff Stamp]

On another forum we were discussing whether locking knives should be trusted or if, in fact, they were designed to do things non-locking knives did.

If they are not, then the blade geometries on the larger tacticals make no sense. If you are going to treat a folder like a slip joint, then get one with a similar ground blade.

-Cliff

 

[Confederate]

Manufacturers pretend that knives will never be used for defense purposes; however, when engaged in situations where someone may be so using a knife, the knife is going to be used in close quarters with a certain amount of force and torque being used. Also, with larger cutting jobs knives may undergo more stress than many folders are used to. It seems to me that locking folders have a purpose a notch or two over non-locking folders. But most reviewers don't take the locking ability of such knives into consideration.

I'd love to be turned loose in some junk yard with a good pair of gloves, some goggles, a hammer and a bunch of good quality knives to test to destruction. I look at CRKT's LAWKS, for example, and it looks like it a good supporting design; however, I've never seen it tested.

Anything mechanical can fail, but should reviewers take a knife's locking ability into consideration or blithely dismiss it by saying that if proper handling is observed, it ultimately makes no difference? I don't think anyone would expect any locking system to turn a folder into a fixed knife, but to argue that locking designs in general are not designed to do anything a non-locking knife couldn't do just about as well may be overstepping a tad. How handy would a Buck 110 be without the blade locking?

-Confed

 

[Cliff Stamp]

Manufacturers pretend that knives will never be used for defense purposes;

Many promote the knives for such as well as other activies which heavily load locks, Cold Steel for example does hard thrusts with their folders. Spyderco even has a specific lock strength rating for martial applications.

I look at CRKT's LAWKS, for example, and it looks like it a good supporting design;

Design yes, implementation no, it is unhardened steel, it bends easily.

... but to argue that locking designs in general are not designed to do anything a non-locking knife couldn't do just about as well may be overstepping a tad.

You will find a large overlap between the people who argue that folders should be all treated like slip-joints and those who promote liners/integrals.

-Cliff

 

[ric0shay]

Any time I use mine I think to stay within the limitations of the knife. I try not to put a load on the blade opposite to the cutting edge.

the only time I remember intentionally putting presure on the back of the blade is when unduing a stubborn knots frope rope. using the back of the blade to scrape PRC (rubber) from a fragile surface that might be easy to gouge with the cutting edge.

"Think twice cut once..."

quote Chris Reeve
Rick

 

[snailgate]

I used one for many years in a chemical research laboratory to cut light guage wire, rubber and plastic tubing, but more importantly, to open metal cans that were used to ship exotic chemicals. These containers had weird seams that an ordinary can opener would not grip.

I would just punch through the metal with the Sod Buster. It had a brass liner lock, with a large tab on the blade end that never collapsed on me. I kept the blade with a sharp chisel edge and it never chipped. Sometimes I used a rubber mallet on the end of the handle to get it started.

For some reason, the locking version of the Sod Buster has not been in the Case catalog for quite a while.

 

[Gryffin]

On another forum we were discussing whether locking knives should be trusted or if, in fact, they were designed to do things non-locking knives did.

"The can is open... the worms are everywhere..."

This is a much discussed topic around here. Oughta get a lot of responses.

IMHO, locking folders occupy an uncomfortable middle ground between slipjoints and fixed blades. T'ain't one, t'ain't t'other. With care, they can certainly be used for operations you'd never do with a slipjoint; however, to treat them exactly as you would a fixed blade is folly. (And possibly a claim to your medical insureance company!)

The problem with the opinions I see around here is that they tend towards absolutes:

• "All locks fail. You must treat all non-fixed blades as if they are slipjoints."
• "All liner locks and frame locks are inherently flawed, and not to be trusted; however, all [TRENDY LOCK DESIGN] locks are infallible, and will never ever fail."
• "I expect to be able to treat a locking folder like a fixed-blade Bowie. Any failure at means the knife is faulty, no matter how it failed."

What you don't hear very often is Common Sense. (Why is it called that, when it's fairly rare?)

• When using a locking folder, avoid applying force in the unlocking direction. (I.e., treat it like a slipjoint, if possible.)
• If you must put stress on the lock, do so with care. Be sure your fingers aren't in the path of the blade; also, be aware of the unlocking mechanism, and don't activate it inadvertantly.
• If you absolutely must put stress on the lock with your fingers in the path of the blade, take every precaution, and work carefully. Some knives have secondary safety mechanisms, such as the LAWKS, or oversize choils that limit damage to a nasty finger pinch, rather than amputation; use them.

What's so difficult to understand about that? The best safety mechanism your knife has is the one between your ears -- USE IT.

 

[Cliff Stamp]

IMHO, locking folders occupy an uncomfortable middle ground between slipjoints and fixed blades.

This is a vast oversimplification, consider the Fulcrum IID vs the Deerhunter. The fixed blade is meant to be a focused cutting tool, the folder is intended for heavy prying, thrusting and torques.

• When using a locking folder, avoid applying force in the unlocking direction. (I.e., treat it like a slipjoint, if possible.)
• If you must put stress on the lock, do so with care. Be sure your fingers aren't in the path of the blade; also, be aware of the unlocking mechanism, and don't activate it inadvertantly.
• If you absolutely must put stress on the lock with your fingers in the path of the blade, take every precaution, and work carefully. Some knives have secondary safety mechanisms, such as the LAWKS, or oversize choils that limit damage to a nasty finger pinch, rather than amputation; use them.

What's so difficult to understand about that?

Lots of things, a heavy thrust for example requires that you put your fingers in the path of the blade if it were to collapse becaue otherwise you can't hold onto the knife when heavy force is applied, this limits the use of the knife.

As well some makers/designers of folding knives will specifically state that the knives are intended to be used in situations where the lock is loaded directly in the vector to close it. This allows a wider scope of work than knives which can't be used in such a manner.

If you make a folding knife with a slim blade then you can make the arguement it is a light cutting tool, but you can't apply the criteria you listed above to folding knives which have far thicker grinds than on many fixed blades, the only reason they have these is too allow for heavy forces to be applied.

-Cliff

 

[Gryffin]

This is a vast oversimplification, consider the Fulcrum IID vs the Deerhunter. The fixed blade is meant to be a focused cutting tool, the folder is intended for heavy prying, thrusting and torques.

Not at all. You merely persist in thinking that those "sharpened prybars" should be treated differently from all other folding knives.

• Any slipjoint can and will fold under minimal force in the "closing" direction about the pivot.
  
• No fixed blade can or will "fold" under stress, since there's no pivot about which to rotate.
  
• Any knife locking mechanism that is capable of being unlocked, is also capable of being unlocked accidentally, and then folding unexpectedly; No knife is perfectly secure in real-world usage.

Looks like my original statement holds up pretty well: locking folders are a compromise between slipjoints and fixed blades.

Let's take your examples now:

• In the case of a heavy-duty folder like the Fulcrum, it can unlock accidentally (eg., white-knuckling the lock under stress).
  
• In the case of the Deerhunter fixed blade, no amount of force can cause the lock to release, because there is no lock. Sure, the blade or handle may break, but so can the blade or handle of a folder, or even a slipjoint.

I won't even try to argue that the Deerslayer won't break under less force than the Fulcrum's lock can endure, which seems to be the core of your argument. However, we're discussing the reliability of locking mechanisms, not the overall strength of one knife vs. another:

Since most of us have been cut at some point in our lives, how much should we trust locking knives? ... Are liner locks inherently unsafe and do they become more unsafe with use? And finally, are some locking knives considered more trustworthy than others?

Nowhere did he ask if any arbitrary fixed blade was stronger overall than any arbitrary locking folder, he asked if locking mechanisms on folding knives were reliable. Your argument, such as it is, is completely beside the point. Once again, Cliff, you're confusing strength with reliability.

 

[Cliff Stamp]

You merely persist in thinking that those "sharpened prybars" should be treated differently from all other folding knives.

Yes, I would expect a folder with a much thicker and more obtusely ground blade to have a wider scope of work the same as I would a fixed blade of similar design. That is certainly how they are promoted. Similar with locks, not all locking knives have the same scope of work, some are significantly stronger and more secure than others.

Any knife locking mechanism that is capable of being unlocked, is also capable of being unlocked accidentally, and then folding unexpectedly; No knife is perfectly secure in real-world usage.

The same is true of any aspect of knife use, what is important is the consistency of the design in terms of the intended scope of work. It makes little sense to put a hugely robust blade on a lock which is easily released under light impacts, torques and other dynamic cutting.

Looks like my original statement holds up pretty well: locking folders are a compromise between slipjoints and fixed blades.

No, that is far too simplistic a point of view, there are slip joints which are more secure than locking folders, several people have made this point because various lock types once released have the blade collapse with no resistance and the effort required to cause the initial release them can be far less than required to close a slip joint with a stiff action, and there are lots of folders which are capable of a wider scope of work than various fixed blades.

In the case of a heavy-duty folder like the Fulcrum, it can unlock accidentally (eg., white-knuckling the lock under stress).

No it can't, the back lock has a cross bolt.

Once again, Cliff, you're confusing strength with reliability.

You may want to check the origional post :

"On another forum we were discussing whether locking knives should be trusted or if, in fact, they were designed to do things non-locking knives did."

The answer is yes, many are specifically promoted for uses which are beyond the scope of work of slip joints because such uses intentionally load the blade so as to directly oppose the lock. The lock is not simply a safety device, it is part of the design to allow the knife to do things which can not be done with out the lock.

In terms of strength vs security, both have the same consequence when it comes to user safety, both a blade breaking dramatically or a lock releasing pose a large risk to the user and thus both limit scope of work. Some releases may also functionally damage the lock, obviously a blade break damages the knife.

I can be a lot more rigerous with the Fulcrum and use it for a much wider scope of work than the Deerhunter because any force which would cause the Fulcrum to unlock/release would have long broken the Deerhunter, it is made to be used for other things and the lock is integral to this design.

Most quality locks should break before they will accidently release, if they do otherwise they are improperly designed because the strength is irrelevant, they are not then functioning as a lock, Steve Harvey made this point years ago.

-Cliff

 

[Confederate]

CRKT may not use hardened steel in their LAWKS system; however, the block is intended only to stop side slippage. Does anyone know of any examples of lock failure with a CRKT, especially the Desert Cruiser design, which is a tactical knife designed for a positive "locked" position (desirable for combat situations)? I mean, it's a tough little tactical, but it's still a liner lock. That never did seem right.

 

[Cliff Stamp]

CRKT may not use hardened steel in their LAWKS system; however, the block is intended only to stop side slippage.

That isn't how it is promoted :

"T[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]he SFs also feature the patented* Lake And Walker Knife Safety (LAWKS®), which effectively turns the folders into fixed blades when actuated."[/FONT]

That is directly off of the CRKT website.

-Cliff

 

[Confederate]

Yes, that's what I'm concerned about. Why would CRKT make such a blatantly misleading statement? I have heard about LAWKS failures, though I haven't documented any todate. Cold Steel has two ostensible liner locks: the Night Force and the Pro-Lite. The locks appear to extend from the liners, but are steel and lock quite a bit more forcibly than other linerlocks. Even then, it's interesting to note, that in their current DVD only the Pro-Lite manages to fail, but only after 70 pounds of reverse force. CS's engineers show the failure, but add that even if someone had been using the knife, the failure wouldn't have sliced any fingers.

The point is, CS generally doesn't use liner lock designs. The one knife design that does employ it is the only one that managed not to hold up under the rigorous tests they like to publicize. Looking at the massive liner lock, I wonder how any standard liner lock could hold up, even with a LAWKS system. Many will say, "Well, you'd be stupid to rely on any linerlock as though it were a fixed blade knife, but that's clearly what CRKT wants people to think.

In short, the LAWKS does not "effectively" (or even remotely) turn their folders into a fixed blade, even though a careful look at the design shows how the blade is pushed against the handles via two blade stabilizing knobs. Certainly this implies that torque can be applied to the knife while the blade also is locked securely by the Lake and Walker safety. The question becomes: How much reverse pressure would it take to force the blade sideways with enough energy to defeat the LAWKS block?

The answer is, no one knows. If everything works the way it does on paper, force is dissipated by the blade knobs laterally and by the LAWKS mechanism for reverse pressures. If it doesn't work in the real world, I reckon they can just call the CRKT owner "Stubby."


-Confed

 

[Cliff Stamp]

How much reverse pressure would it take to force the blade sideways with enough energy to defeat the LAWKS block?

If you are talking about loads on the spine, not a significant amount, I have done it.

-Cliff

 

[Confederate]

Really? Can you elaborate? I'm really very interested in this. -Confed

 

[allenC]

On another forum we were discussing whether locking knives should be trusted or if, in fact, they were designed to do things non-locking knives did.

I think that a locking knife is more trustworthy than a non-locking knife.
Even though we all know the proper way to use a slip-joint (hopefully), we are but human and mistakes happen--a locking knife is more forgiving of our errors than a non-locking one.

Some locking knives were certainly designed for different tasks than non-locking knives, but most are to be used in the same manner as a slip-joint.

Since most of us have been cut at some point in our lives, how much should we trust locking knives?

As much as you would trust any knife.
There's no getting around the fact that knives can be dangerous and unforgiving--just like firearms.

If I'd been cut, would it have been my fault or the fault of the knife?

This one's a tough call since I don't know exactly how you were using the knife or the nature of the lock failure.
Did it break?
Did it fail to completely lock?
Could you have accidentally unlocked it yourself?
Was there oil, pocket-lint, chapstick, dirt or anything else affecting the lock?

I've cut myself numerous times in my life and I can honestly say that it was my own fault every single time.

Are liner locks inherently unsafe and do they become more unsafe with use?

I once thought so, but not anymore.
Thousands of folks use liner-locks everyday, so it seems that if it is made right from the beginning, it will work.

And finally, are some locking knives considered more trustworthy than others?

I would say that the Benchmade Axis-lock is more trustworthy than most locks.
I say this because every Axis-lock knife is made my ONE company.
Imagine if EVERY liner-lock in the world was made by Spyderco....

If you only count locks that are not proprietary, then I would say that the bali-song style latch-lock is more trustworthy than about any other lock around.
I've never seen or even heard of a person being injured by a bali-song because of lock failure.

Allen.

 

[Cliff Stamp]

Why would CRKT make such a blatantly misleading statement?

Because it will likely sell knives. It isn't just CRKT of course, lots of people promote the use of locking folders for very demanding applications in which very high forces are being applied, if you stick a 3/16" blade in a folder you are obviously not meaning for it to be a low stress cutting tool any more.

Really? Can you elaborate?

The LAWK's works well under torques, but you can't really apply any significant loads by torques anyway because you are limited to what your wrist can exert and that is just tiny compared to normal forces you exert on a knife during heavy cutting. However if the spine is loaded, the LAWK's bar will just bend/deform as it is unhardened steel which is very thin, once it starts to deform you can fully close the blade with your hand with the LAWK's engaged, it will just get smashed to the side. It doesn't take much of an impact, nothing near batoning for example, and no where near the raw strength of the actual liner lock.

-Cliff